The design of certain types of vehicle body styles necessitates the storage of the spare tire under the vehicle, and this mode of spare tire storage is of particular advantage with compact pickup trucks and other utility vehicles. In such installations winch means are mounted upon the vehicle upon which a cable is wound, and a spare tire is attached to the free end of the cable and drawn upwardly against the vehicle undercarriage for storage purposes. When the spare tire is required, the winch is "unwound" lowering the tire to the ground for access and use.
Devices of the aforedescribed type are shown in U.S. Pat. Nos. 2,688,372; 3,542,413; 3,372,821; 3,395,819; 3,734,323; 3,856,167; 3,874,536 and 4,059,197.
Present tire carriers of the type generally described in the aforementioned patents primarily utilize winch drives of the general construction shown in U.S. Pat. No. 4,059,197 wherein an eccentric gear arrangement is employed to provide a mechanical advantage in the operation of the winch. However, known under-vehicle tire carriers may malfunction due to difficulty with the winding of the cable upon the winch sheave. For instance, if the winch is rotated in the improper direction difficulty occurs in raising the tire in the proper manner, and if the tire is not snugly drawn against its supporting surfaces excessive wear and noise occur and the possibility of inadvertently releasing the spare tire is present.
It is most important that tire carrier apparatus of the aforedescribed type be dependable in operation, yet simple in construction and function, as the apparatus is not readily accessible to the user, and must be automatically capable of performing its desired function once the crank has been attached thereto.
Also, as the most desirable location for under-vehicle tire storage may be remote from the rear of the vehicle, which is the location from where the winch is usually operated, difficulty is often encountered in attaching the manual crank to the winch, and present constructions limit the location of tire storage due to the necessity for easily attaching the manually operated winch crank to the winch driveshaft.
It is an object of the invention to provide a winch type tire carrier utilizing a cable wound upon a sheave wherein the winch sheave is prevented from being rotated in a nonoperative direction.
Another object of the invention is to provide a tire carrier winch system utilizing a cable wound upon a sheave wherein the orientation of the cable to the sheave is sensed, and upon the cable being fully extended, stop means prevent winding of the sheave in the improper direction.
Another object of the invention is to provide a winch type tire carrier with an anti-rotation sheave lock which is of a concise configuration and automatically prevents excessive winch sheave rotation of sheave winding in the improper direction.
A further object of the invention is to provide a winch type tire carrier with torque limiting means to prevent excessive cable stress during tire storage.
Yet another object of the invention is to provide a winch type tire carrier utilizing a cable wound upon a sheave wherein a cable extension and guide permits tire storage at a location remote from the winch.
In the practice of the invention a concise low cost winch mounted within a sheet metal housing is attached to the underside of a motor vehicle. By means of a manual crank attachable to the winch driveshaft, the winch may be operated to lower a spare tire from a storage position engaging the vehicle undercarriage to an access position upon the tire being lowered to the ground. Gear reduction means of an eccentric type provide the winch with a high mechanical advantage, and the invention utilizes cable position sensing means to prevent rotation of the cable winch in an improper direction during cable retrieval.
The cable extends through an opening in the winch housing, and a cable sensing block within the housing through which the cable passes maintains a predetermined orientation to the housing as the cable is wound and unwound with respect to the winch. However, upon the cable being fully extended, and attempted rotation of the winch sheave in the improper direction for cable retrieval, the block is displaced within the housing due to the relocating of the cable relative to the sheave and housing opening. Such displacement of the cable sensing block actuates a dog engaging the winch sheave drive mechanism immediately preventing further rotation of the sheave in the improper direction. Correction of the direction of winch rotation automatically actuates the cable sensing block to release the winch restraining detent permitting normal operation.
The winch utilizes torque limiting means to prevent excessive cable tension consisting of a plurality of spring drive members resiliently engaging notches within a winch drive plate such that excessive resistance to cable movement permits the spring drive members to ride out of the associated notches and thereby limit the torque applicable to the winch drive mechanism.
Location of the winch housing at a mounting point spaced from the tire storage location is achievable with an embodiment of the invention by means of an elongated cable guide and extension closely receiving the cable exteriorly of the winch housing. The free end of the guide is mounted to the vehicle underside, and the guide closely supports the cable to minimize binding problems during cable extension under no load conditions.